
//@HEADER
// ************************************************************************
// 
//               HPCCG: Simple Conjugate Gradient Benchmark Code
//                 Copyright (2006) Sandia Corporation
// 
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
// license for use of this work by or on behalf of the U.S. Government.
// 
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//  
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//  
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA
// Questions? Contact Michael A. Heroux (maherou@sandia.gov) 
// 
// ************************************************************************
//@HEADER

#ifndef COMPUTE_RESIDUAL_H
#define COMPUTE_RESIDUAL_H

#include "adapt.h"
#include <cmath>  // needed for fabs
using std::fabs;

namespace adapt {

int compute_residual(const int n, const AD_real * const v1, 
		     const double * const v2, AD_real * const residual)
{
  AD_real local_residual = 0.0;
  
  for (int i=0; i<n; i++) {
    AD_real diff = fabs(v1[i] - v2[i]);
    if (diff > local_residual) local_residual = diff;
  }
  
  *residual = local_residual;

  return(0);
}

}

#endif
